ML14139A380
| ML14139A380 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 05/14/2014 |
| From: | Michael Lee Enercon Services, Entergy Nuclear Operations |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML14139A374 | List: |
| References | |
| OCAN051402 CALC-ANO1-CS-12-00003, Rev 1 | |
| Download: ML14139A380 (20) | |
Text
Attachment I to OCAN051402 Arkansas Nuclear One, Unit I (ANO-1) Revised Flooding Walkdown Report Engineering Report Number CALC-ANO1-CS-12-00003 Rev. 1 Page 1 of 19==-En tety ENTERGY NUCLEAR Engineering Report Cover Sheet Engineering Report Title: Arkansas Nuclear One Unit I Flooding Walkdown Submittal Report for Resolution of Fukushima Near-Term Task Force Recommendation 2.3: Flooding Engineering Report Type: 0 Cancelled El Superseded New El Revision IPi El AN01 Q IP2 El ANO2 IP3 E]ECH El Applicable Site(s)JAF Li PNPS El GGNS [I RBS [1 VY E] WPO El WF3 [I PLP El EC Number 50803 Report Origin: El Entergy [E Vendor Vendor Document Number: CALC-ANO1-CS-12-00003 Quality-Related:
El Yes El No Prepared by: Design Verified/Reviewed by: Reviewed by: ENERCON /Responsible Engineer (Print Name/Sign)
N/A Date: Design Verifier (if required) (Print Name/Sign)
Chris Johnson / See Asset Suite Reviewer (Print Name/Sign)
N/A ANII (if required) (Print Name/Sign)
Date: Date: See AS Date: Date: See AS Approved by: Ed Blackard / See Asset Suite Supervisor (Print Name/Sign)
Revision.
Record of Revision Initial issue.0 CALC-ANO1-CS-12-00003 is revised to report the results of the 2012, 2013, and 2014 flood protection walkdowns for Arkansas Nuclear One Unit 1 that 1 were completed following the guidance of NEI 12-07, "Guidelines for Performing Verification Walkdowns of Plant Flood Protection Features".
-I CALC-ANOI-CS-1 2-00003 OENERCON"'r-ntrg REV. I Page 3 of 19 ENGINEERING REPORT ARKANSAS NUCLEAR ONE UNIT 1 FLOODING WALKDOWN SUBMITTAL REPORT FOR RESOLUTION OF FUKUSHIMA NEAR TERM TASK FORCE RECOMMENDATION 2.3: FLOODING Prepared By: Reviewed By: Peer Reviewed By: Approved By: Michael Lee (Enercon Services, Inc.)Eric(,'abtrEnercon Services, Inc.)Wavel Justice (Enercon Services, Inc.)Atwood A. Browning (Enercon Inc.)Date: I Date: to Date: _____ '_, Date: _ _ _ _
CALC-AN01 -cs-i 2-00003 E ENERCON Ente7gy REV. 1 ,,-oofl( Page 4 of 19 TABLE OF CONTENTS Section Title Paqe 1.0 SCO PE AND O BJECTIVE ..................................................................................
5 2.0 DESIG N BASIS FLOO D HAZARD LEVEL .......................................................
5 2.1 Flood Hazards Identified
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5 2.2 Assum ptions ...........................................................................................
6 2.3 M ethodology
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7 2.4 Non Conformance
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7 3.0 EXTERNAL FLOOD PROTECTION AND MITIGATION FEATURES ................
7 3.1 Flooding Licensing Basis ..........................................................................
7 3.2 Flood Duration .........................................................................................
8 3.3 Flood Protection Features .......................................................................
8 3.4 Procedures
.............................................................................................
9 3.5 Adverse W eather ....................................................................................
9 4.0 INTERNAL W ARNING SYSTEMS ....................................................................
9 4.1 Room W ater Level W arning Systems .....................................................
9 5.0 EFFECTIVENESS OF FLOOD PROTECTION SYSTEMS ...............................
10 5.1 Acceptance Criteria ................................................................................
10 5.2 Discussion
.............................................................................................
12 6.0 IM PLEM ENTATIO N O F W ALKDOW NS ..........................................................
13 6.1 Flood Protection W alkdowns .................................................................
13 6.2 NEI-12-07 Guidance .............................................................................
14 6.3 Team Organization
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14 6.4 Training Approach ..................................................................................
15 7.0 W ALKDOW N RESULTS ..................................................................................
15 7.1 Deficiencies
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16 7.2 O bservations
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16 7.3 Corrective Actions ..................................................................................
17 7.4 Flood Protection Features Not Inspected
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17 8.0 AVAILABLE PHYSICAL M ARG IN ..................................................................
18 9.0 NEW FLOO D PROTECTION SYSTEM S ..........................................................
18
10.0 REFERENCES
................................................................................................
18 11.0 ATTACHM ENTS ...............................................................................................
19 O CALC-ANO -cs-i 2-00003 0 ENERCON REV. 1 E-,,, ,Page 5 of 19 1.0 SCOPE AND OBJECTIVE This report was developed to provide information requested by the United States Nuclear Regulatory Commission (NRC) pursuant to Title 10 of the Code of Federal Regulations (CFR), Section 50.54(f) on March 12, 2012, for Arkansas Nuclear One (ANO) Unit 1 (Ref.10.1). In response to the NRC request, Entergy performed walkdowns to verify that plant features credited in the current licensing basis (CLB) for protection and mitigation from external flood events are available, functional, and properly maintained.
The walkdowns were performed to verify that structures, systems, and components (SSCs), portable flood mitigation equipment, and the procedures needed to install and/or operate them during a flood are acceptable and capable of performing their design function as credited in the CLB.This report presents the findings of the flooding walkdown inspections completed at ANO Unit 1 in 2012, 2013, and 2014, as discussed in Section 6.1 of this report. The walkdowns were completed following the NRC endorsed guidance of Nuclear Energy Institute (NEI)12-07, Rev. 0-A, Guidelines for Performing Verification Walkdown of Plant Flood Protection Features (Ref. 10.4) and Entergy Nuclear procedure EN-DC-170 (Ref. 10.5)that was developed to provide instructions for implementation of the NRC endorsed guidelines.
In addition to verifying that site flood protection features are acceptable and capable of performing their design function, the walkdowns were also used to verify that plant modifications implemented since original construction, such as changes to topography, do not adversely affect flooding protection.
This report identifies the flooding hazards that comprise the CLB and the protection and I mitigation features that are credited with preventing the ingress of external water into safety-related SSCs at ANO Unit 1. The effectiveness of the flood protection features is evaluated against a set of acceptance criteria.
Results of the walkdowns, including key findings, available physical margin, and any identified degraded, or nonconforming conditions are addressed, and a description of the actions taken or planned to address these conditions is provided.2.0 DESIGN BASIS FLOOD HAZARD LEVEL Sections 2.4 and 5.1.6 of the ANO Unit 1 Safety Analysis Report (SAR) (Ref. 10.6)describe the design basis and flood protection features provided at ANO Unit 1 for protection against an external flood, respectively.
2.1 Flood
Hazards Identified ANO Units 1 & 2 are adjacent nuclear plants located on a peninsula that extends into the Dardanelle Reservoir.
The plant is centrally located on the peninsula with a grade elevation (near the center of the site) of 353' above Mean Sea Level (MSL). The peninsula is about two miles wide and two miles long. The plant is surrounded on three sides by the Dardanelle reservoir.
The shortest stretch of land is approximately one mile in a southeast direction.
The ground surface surrounding the plant is predominantly meadow.
The Dardanelle Reservoir is part of the Arkansas River navigation project. The Dardanelle Dam impounds the Arkansas River, creating the Dardanelle Reservoir (also known as Lake Dardanelle).
The dam is managed and controlled by the United States Army Corps of Engineers (USACE). The level of the reservoir fluctuates between 336' (normal pool) and 338' (maximum controlled pool) above MSL. The upper end of the Dardanelle Reservoir lies beneath the Ozark Dam, which is approximately 51 miles upstream.The safety-related structures, or Seismic Class 1 structures, at ANO Unit 1 are capable of withstanding the worst flooding caused by a combination of hypothetical events. The Probable Maximum Flood (PMF) level is 358' above MSL considering maximum probable flooding flows and a maximum flood level on the downstream side of the Ozark Dam. An instantaneous failure of the Ozark Dam coupled with the PMF results in a maximum potential flood level of 361' MSL. The effects of wind and wave action on a PMF event would add approximately 2.5' to the PMF of 358' MSL, or approximately an effective 360.5' MSL flood level. Therefore, the combined effects of wave action and PMF are bounded by the combination of a hypothetical Ozark Dam failure event and PMF event and thus the design flood elevation for ANO Unit 1 was determined to be 361' MSL. According to the ANO Unit 1 SAR, Seismic Class 1 equipment is protected from splash effects up to 10'above the PMF level of 358' MSL (i.e. 368' MSL) as follows: "All Class 1 structures are designed to resist this flood and all Class 1 equipment is either located above elevation 369 feet or protected from flooding by the Class 1 structures." Groundwater intrusion into safety-related structures is considered a potential source during flooding events. The design of the Seismic Class 1 structures considers the source as credible and provides protection against groundwater intrusion into these structures as low as the base grade level at elevation 317'MSL.With respect to probable maximum precipitation, there are no AN 0 Unit 1 SAR commitments.
However, as an ANO response to NRC Generic Letter 88-20 (Ref.10.3), the site is required to provide drain and scupper inspection on the Unit 1 roof. These actions ensure the drains and parapet scuppers are not blocked and thus can be counted upon to provide adequate drainage in the event of local intense precipitation.
This ensures that structural roof loads due to ponding effects are not exceeded.2.2 Assumptions No assumptions apply to establish a CLB thr eshold with respect to wind and waves. As discussed above the effect of wind and waves were considered but were bounded by the combination of a PMF and Ozark Dam failure events and thus do not apply.With the exception of watertight doors and hatches, the ANO Unit 1 SAR is silent with respect to non-piping penetrations being a credible flooding pathway.Therefore, it is assumed that when the SAR refers to piping penetrations being sealed, it implicitly also includes conduit, HVAC, and other similar penetrations that pose a credible flooding pathway and that they should be similarly sealed.
2.3 Methodology
The PMF for the Arkansas River is estimated based upon the projected flood defined by the USACE (Ref. 10.6). USACE has computed the maximum probable flood flow at the Dardanelle Dam as 1,500,000 cubic feet per second. At this flow, the water level at the Dardanelle Dam would be 353' MSL. The upper end of the Dardanelle Reservoir is at the Ozark Dam, about 51 miles upstream.
During PMF conditions, the level of the Dardanelle Reservoir at the downstream side of Ozark Dam would be 389.5' MSL. No profile for t his condition is available, but it is reasonable to assume a straight-line variation.
On this basis, the PMF level at the plant site is 358' MSL.Wind and wave activity are considered but are bounded by the possibility of a coincidental Ozark dam failure with the PMF. For the purpose of the estimate of wind and wave activity, the results indicate an approximately 2.5' increase in effective flood level and utilized a calculation input for wind speeds of 45 mph from the south west direction and a fetch of 18,000' (Ref. 10.6).Evaluation of the instantaneous and coincidental Ozark dam failure with the PMF determines a theoretical water level rise of 6.8', but then describes this outcome as"so unlikely as to be practically impossible." The estimate uses a uniform river channel assumption which is considered very conservative.
Furthermore, an additional 50 square miles of flood plain would be a consequence not accounted for in the original computations and it would result in a "great amount of extra storage".
Therefore, the calculation estimates a 3' rise in flood elevation over the PMF level of 358' MSL. Thus, t he overall design basis for the ANO site was calculated to be 361' MSL.2.4 Non Conformance No differences or contradictions in flood hazard levels were found in design or licensing basis documentation.
3.0 EXTERNAL
FLOOD PROTECTION AND MITIGATION FEATURES 3.1 Flooding Licensing Basis The safety-related structures at ANO are designed to withstand the worst flooding caused by a combination of hypothetical events. These events are the probable maximum flood of the Arkansas River coinciding with the Ozark Dam failure.Based on the ANO CLB, the current maximum design basis flood level is 361'MSL. Critical components and equipment are protected by flood rated Seismic Class 1 structures or placed at elevations above 369' to protect against splash effects.The following Seismic Class 1 structures are desi gned to withstand external flooding:
Unit 1 Reactor Building, Unit 1 Auxiliary Building, Emergency Diesel Fuel Storage Vaults, and the Post Accident Sampling System (PASS) Building, and portions of the Unit I Intake Structure that house the Service Water System.
CALC-ANO1 -CS-1 2-00003 ENERCON REV. 1 S -Page 8 of 19 As discussed in Section 2.1 of this report, in order to address NRC Generic Letter 88-20 (Ref. 10.3), ANO has made a licensing commitment to ensure that Unit 1 I Auxiliary Building Roof Drains and Scuppers are unblocked in order to allow adequate drainage to avoid exceeding the roof structural design basis. The addition of scuppers to the parapets along the Unit 1 Auxiliary building roof and the routine surveillance to ensure both scuppers and drains are unblocked provides assurance that there is the required drainage to withstand local intense precipitation events without compromising the structural integrity of the roof.3.2 Flood Duration Section 8.3.1.1.7.2 of the ANO U nit 1 SAR (Ref. 10.6) states that a PM F is expected to be above plant grade elevation, 353' above MSL, for a duration of two to five days.3.3 Flood Protection Features Safety-related systems and components are flood protected either because of their location above the design basis flood level, or because they are enclosed in reinforced concrete Seismic Class 1 structures.
The Seismic Class 1 structures that may be affected by a design basis flood at the site are designed to withstand the postulated floods for the site using the "hardened" flood protection approach, per ANO Unit 1 SAR, Section 5.1.3 (Ref. 10.6). The hardened protection approach means structural provisions are incorporated in the plant's design that will protect safety-related structures, systems, and components from the static and dynamic effects of a flood. As part of the hardened approach, watertight doors and equipment hatches as well as watertight piping and electrical penetrations are installed below the maximum flood level.As stated in the ANO Unit 1 SAR, each of the Seismic Class 1 structures discussed in Section 3.1 of this report is protected by the following design criteria:* Wall thicknesses below flood level are a minimum of two feet.* Waterstops that are provided in construction joints below flood level.* The number of openings in walls and slabs below flood level are kept to a minimum." Waterproof doors and equipment hatches are installed.
- Possible local seepage through the walls will be controlled by sumps and sump pumps.With respect to the Reactor Building, the Equipment Hatch, and the Building Escape Hatch are double sealed openings.
The Tendon Gallery Access Hatch is protected using a water tight hatch cover.With respect to the Auxiliary Building, door openings are protected utilizing watertight doors; floor openings are protected utilizing watertight hatch covers; roof openings over underground vaults are protected utilizing concrete plugs with neoprene seals; conduit and HVAC penetrations are externally and internally sealed as necessary, and pipe penetrations are protected utilizing seals or closure plates.
CALC-ANO1 -CS-1 2-00003 E ENERCON REV. 1&,y icy. E nlte? 3 Page 9 of 19 With respect to the Emer gency Diesel Fuel T ank Vaults, door o penings are protected utilizing watertight doors; roof openings are protected utilizing concrete plugs with neoprene seals; conduit penetrations are externally and internally sealed, and pipe penetration are protected utilizing seals or closure plates.With respect to the PASS building, door openings are protected utilizing watertight doors; conduit penetrations are externally and internally sealed; and pipe penetrations are protected utilizing seals or closure plates.3.4 Procedures ANO Unit 1 operating procedure for natural emergencies describes the actions to be taken in the event of plant flooding caused by natural phenomena at the site.This procedure provides actions to be taken based on different levels of the Dardanelle Reservoir as measured at the Unit 1 Intake Structure.
In order to maintain offsite power to the plant, temporary jumper cables are installed from the 161 kV Pleasant Hill transmission line to Startup Transformer
- 2.ANO's site preventative maintenance procedures address the required maintenance for components, such as doors and hatches, utilized in procedural actions in order to maintain flood protection.
The inspection interval of the doors and seals is not associated with a specific water level or flood situation at ANO but is established as part of the maintenance work order planning system.Entergy Corporate procedures associated with condition monitoring of maintenance rule structures, per 10 CFR 50.65, provide the programmatic instructions for preventative maintenance and surveillance for the Seismic Class 1 structures that are protected from flooding.3.5 Adverse Weather In accordance with the ANO Unit 1 operating procedure for natural emergencies, flood protection measures are required to be installed, such as temporary flood barriers, for protection of safety-related systems and components during flooding conditions.
Based on the CLB, Unit 1 watertight doors are assumed to remain closed or be verified as closed during a flooding event. The ANO Unit 1 natural emergencies procedure provides instructions to secure the doors as part of the response in accordance with anticipated and measured flood levels. Some doors and hatches cannot be accessed without requiring personnel to travel outdoors.However, these doors and hatches are maintained in a normally closed position, I thus adverse weather impacts are not considered a credible hindrance to th e flooding response.4.0 INTERNAL WARNING SYSTEMS 4.1 Room Water Level Warning Systems No interior water level warning systems or alarms are credited for external flood protection in the plant's CLB.
EEEt- 10CALC-ANO1 -CS-1 2-00003 ENERCON REV. 1 Page 10 of 19 5.0 EFFECTIVENESS OF FLOOD PROTECTION SYSTEMS 5.1 Acceptance Criteria The flood protection features credited in the CLB for Arkansas Nuclear One Unit 1 are incorporated active and passive features and include watertight doors and door seals, exterior structural walls, penetration seals through exterior walls, neoprene sealed hatches, sumps, sump pumps, check valves, and Reactor Building, Auxiliary Building and Tendon Gallery equipment and escape hatches. The site topography, and existing drainage ditches and culverts are not licensing basis credited features for flood protection although natural drainage patterns and drainage designs are consistent with ensuring that flood waters drain away from protected areas and that critical equipment and systems are in elevated areas where applicable.
These flood protection features were visually inspected following the acceptance criteria described in NEI 12-07, Section 6 (Ref. 10.4) document and as discussed below.ANO Unit 1 maintenance procedure for watertight doors was used as a reference to determine the acceptance criteria for the doors. Based on the instruction, the seals are to be installed between the door and the frame, with the seal being slightly compressed and maintaining solid contact at all locations.
Therefore, with the door closed, the seal was visually inspected to ensure no gaps are seen between the seal and the door. The door was then opened to inspect the seal and ensure that no visible cracks or deterioration was present. The sealing mechanisms and latches were inspected for functionality.
The seal was determined to be acceptable if there appeared to be contact between the seal and door at all points, no degradation or deterioration on the seal was observed, and the seals on the doors were installed to an elevation that ensure the door was protected to the maximum elevation of 361' MSL.Seismic Class 1 structures at ANO Unit 1 are protected from the effects of a design basis flood based on the hardened flood protection approach and include the following structures:
the ANO Unit 1 Reactor Building, the ANO Unit 1 Auxiliary Building, the Emergency Diesel Fuel Vault, the PASS Building, and portions of the Intake Structure.
The hardened approach requires structural provisions, such as watertight doors and penetrations to be incorporated into the plant design to protect safety-related structures, systems, and components from the effects of a flood. Based on the hardened approach the following walls, ceilings, and floors, including the associated penetrations, were required to be walked down as they were located on the exterior of the structure and were not shielded from potential flooding by ot her structures:
the exposed Western portion of the ANO Unit 1 Reactor Building at elevations 335' and 354'; the North, South, East and West exterior walls of the ANO Unit 1 Auxiliary Building at elevations 317', 335', and 354'; the exterior North, South East, West Walls and associated ground level covers of the Emergency Diesel Fuel Vault; and the exterior PASS Building West wall at elevation 354' and East wall adjoining the ANO Unit 1 Auxiliary Building at elevation 354'. The walls and penetrations act as an ex ternal flood barrier and prevent water intrusion into the structures.
Groundwater may be present near the ground surface, therefore flooding sources from below the ground surface are considered.
Exterior walls below grade were inaccessible from the outside; therefore, the walls were inspected from the interior.Drainage characteristics associated with site topography are not a credited CLB feature. However topography was visually inspected against the ANO site drainage drawings.
The walkdowns visually verified that the topography of the site allowed water to drain as depicted in the drawings.
Engineering changes including those completed for security reasons were reviewed to ensure that any obstructions or changes made to the site did not adversely impact site flooding protection.
Per the ANO response to NRC Generic Letter 88-20 (Ref. 10.3), the site is required to provide drain and scupper inspection on the Unit 1 Auxiliary Building roof to ensure the drains and scuppers are not blocked in order to provide adequate drainage and limit roof ponding, which is not to exceed structural design limits in the event of local intense precipitation.
The Unit 1 Auxiliary Building roof scuppers and roof drains are maintained free from debris and blockage.
Walkdowns were completed to confirm the Unit 1 Auxiliary Building roofs were free of any potential blockage or debris that could impede roof drainage.Portions of the ANO Unit 1 Intake Structure are Seismic Class 1 structures.
Walkdowns were completed in these areas to determine if Seismic Class 1 equipment in these areas was adequately protected against flooding.
Equipment inspected includes control boards, switchgear, load centers, batteries, transformers and cable runs serving Seismic Class 1 equipment.
The Seismic Class 1 equipment is namely the Service Water System, which includes service water pumps, valves, connecting piping, and intake structure sluice gates. Equipment likely to be rendered inoperable due to flooding was walked down to determine if the equipment was protected by a Seismic Class 1 structure or whether the equipment was above the 369' elevation.
The ANO Emergency Cooling Pond Intake and Discharge Structures are Seismic Class 1 structures, but are not specifically discussed in the CLB as providing flooding protection.
These areas were walked down to ensure that protection was evident in the event flooding was to occur that might transport debris and render these systems inoperable due to blockage.
The acceptance criteria for these features were to verify the presence of trash racks and debris blocking features.Unit 1 Auxiliary Building sumps and sump pumps are a cr edited licensing basis flood protection measure. Therefore sumps, sump pumps, and levelI instrumentation were visually inspected following the acceptance criteria described in NEI 12-07 and EN-DC-1 70 (Ref. 10.5).ANO Unit 1 operating procedure for natural emergencies provides instructions for site responses to flooding events. Section 6.12 of this procedure provides the instructions to contact a third party to install jumpers from the Pleasant Hill 161 kV transmission line to the Startup Transformer
- 2.
CALC-ANO1 -CS-1 2-00003 ENERCON Jo tergy ,REV. 1 n"O"ec".E'rrday n t ePage 12 of 19 The ANO Unit 1 operating procedure for natural emergencies was tested, via a Reasonable Simulation, in a step-by-step manner through posing questions to address the guidance found in NEI 12-07, Section 5.5.6. Namely: 1. Can the procedural step be executed as written?2. Can any time dependent activities be completed in the time frame required?3. Are specified equipment or tools properly staged and in good working order?4. Will completion of the activity not be impeded by the flood event?5. Is it certain that there is no over reliance on the staff and that the staff can complete the necessary steps?The acceptance criteria are positive answers to the above questions against each procedural step.Observations which were not immediately able to be judged as acceptable on the walkdowns were entered into the ANO Corrective Action Program (CAP) to allow for a more detailed evaluation to be completed (See Section 7.1 for deficiencies).
5.2 Discussion
5.2.1 Overall
Effectiveness The ANO Unit 1 flood protection and mitigation features were either determined to be operable as found, promptly repaired to restore operability, or addressed with compensatory measures to maintain operability.
These determinations are based on results of the operability determinations associated with the observations that were entered into the site CAP system.Except as noted in Sections 7.1 and 7.2;Walls, ceilings, floors, and penetrations located below 362', 1' above the CLB flood level of 361', were walked down to ensure no credible flood pathways exist and to support available physical margin (APM)determination (Ref. Section 8.0 of this report).Doors and door seals were observed to ensure the proper operation of water tight doors, and were found to be in working order with proper seals, and that their function would not allow flooding of structures.
Site topography, although not a credited flood protection feature, was verified against site drainage drawings and was determined to not direct flood waters towards protected features.Critical water-sensitive equipment and components installed in the Unit 1 Intake Structure Building were observed to be above CLB 361' MSL.Furthermore, they were confirmed to be splash protected.
The Emergency Cooling Pond Intake and Discharge structures were confirmed to have debris blocking features.Unit 1 Auxiliary Building Roof Drains and Scuppers were observed to be free from debris and able to provide the required drainage.
ECALC-AN0o -cs-i 2-00003 SENERCON REV. 1 Exceerv D'jyy Page 13 of 19 The Unit 1 Auxiliary Building sump pumps and level instrumentation were observed to be in working order and were verified as being maintained.
The reasonable simulations applied to the ANO Unit 1 operating procedure for natural emergencies posed 5 guidance questions, per NEI 12-07, Section 5.5.6 (Ref. 10.4). These questions were to be answered in the affirmative for each of the procedural steps in order for the simulation of each step to be acceptable.
During the walkdowns, conditions that did not meet the acceptance criteria discussed in Section 5.1 of this report were entered into the CAP at ANO.5.2.2 Other SSCs and Procedures Entergy Corporate procedures associated with the Maintenance Rule Program provide the guidance and requirements for conducting a structural condition monitoring program to meet the requirements of 10 CFR 50.65. At ANO Unit 1, Maintenance Rule walkdowns are conducted a minimum of every five (5) years and are completed in accordance with the procedures.
This program provides a systematic approach for evaluation of plant systems/structure which will provide a reasonable assurance that the structures are capable of fulfilling their design basis functions.
The program consists of periodic reviews of the condition of the plant structures via periodic inspections, routine walkdowns, surveillance tests, and ongoing review of the effect of the condition of plant structures on significant plant equipment.
The program consists of defining and performing periodic structural evaluation which will ensure the timely identification, assessment, and repair of degraded structural elements.
Concrete structures and penetration seals are inspected for cracking, spalling, erosion, corrosion of reinforcing bars, settlement, deformation, leaching, discoloration, groundwater leakage, rust stains, exposed rebar, rust bleeding, and other surface irregularities.
Flood barriers and seals, watertight doors, hatches, and internal conduit seals, were determined to be within the scope of the Maintenance Rule procedure and are, therefore, examined in accordance with this procedure.
Maintaining the structures and materials monitored under this procedure provides a reasonable assurance that those structures, that fall under the program, will be able to per form their intended function.The Auxiliary Building and Emergency Diesel Fuel Vault are equipped with floor drainage systems. Water entering these structures would flow across sloped floors and enter the floor drainage systems to be collected in sumps at the bottom floor elevations.
The CLB takes credit for the control of local seepage through walls via sumps and sump pumps.6.0 IMPLEMENTATION OF WALKDOWNS 6.1 Flood Protection Walkdowns Walkdowns were organized for ANO Unit 1 in 2012 using the NEI 12-07 guidance (Ref. 10.4). The walkdowns performed in 2012 inspected flood protection features and attributes.
Discrepant conditions were identified and entered into the CAP.
CALC-ANO1 -CS-1 2-00003 SENERCON I___g REV. 1 Page 14 of 19 Summary reports were submitted to the NRC to document the performance of the flood protection walkdowns in accordance with NRC Letter to Licensees (Ref.10.1), which included a list of restricted access features requiring inspection by September 30, 2013 (Refs. 10.7 and 10.8). In 2013, the restricted access features were inspected.
However, following review of the 2012 flood protection walkdown report and observations during the 2013 walkdowns, it was discovered that discrepancies existed in the 2012 walkdown report that required additional walkdowns to resolve (Ref. 10.9). These discrepancies were entered into the CAP.Based on an assessment of the 2012 flood protection walkdown report for ANO Unit 1, walkdowns were performed in 2014 to address discrepancies.
A majority of the 2012 walkdowns were re-performed.
Examples of these discrepancies were associated with ductwork, ceiling/floor areas, and embedded features such as floor drain connectivity and embedded conduit routing.6.2 NEI-12-07 Guidance The verification walkdowns were performed following the guidance of the NRC endorsed NEI 12-07 (Ref. 10.4) and Entergy Nuclear procedure EN-DC-170 (Ref.10.5) that was developed to provide instructions for implementation of the NRC endorsed guidelines.
Additional guidance for implementation was also obtained from the NEI 12-07 Frequently Asked Questions (FAQs) and the NRC Request for Additional Information (RAI) (Ref. 10.2).The basis for establishing the walk down scope and the flood protection and mitigation features included the preparation of a walkdown list following the guidance provided in NEI 12-07, Section 4. As part of this preparation, the CLB was reviewed to determine the flood protection and mitigation features and actions that are necessary to prevent an external flooding event at the site from adversely impacting safety-related SSCs. In addition to the identification of passive and active flood protection and mitigation features, existing site and Entergy Corporate procedures were reviewed to determine if any procedures were necessary to ensure existing flood protection and mitigation features would be functional in the event of a flood at the site.Walkdown packages were prepared following the guidance provided in NEI 12-07, Section 5.2 and walkdown team personnel were selected based on the requirements provided in NEI 12-07, Section 5.3.Prior to each walkdown, a pre-job brief was conducted.
Walkdown results were documented in accordance with the recommendations of NEI 12-07, Section 7 on the Flooding Walkdown Record Form provided in Attachment 9.3 of EN-DC-170.
The walkdown record form provided in Attachment 9.3 is consistent with the record form template provided in Appendix B of NEI 12-07.6.3 Team Organization Consistent with NEI 12-07, Section 5.3 (Ref. 10.4), the walkdown team consisted of two trained individuals with a complementary set of skills. The walkdown team consisted of two degreed engineers (or equivalent), who had familiarity with the site. During the 2012 walkdowns, the walkdown team was su pplemented, as CALC-ANO1 -CS-1 2-00003'"ENERCON REV. 1 Exef-"e7 E nty Page 15 of 19 required, by plant maintenance and/or operations personnel.
For the 2014 walkdowns, Entergy provided qualified engineering personnel to provide oversight of the inspections and review of the findings.6.4 Training Approach Consistent with Section 5.3 of NEI 12-07 (Ref. 10.4) and Section 4.1 of EN-DC-170 (Ref. 10.5), personnel selected to perform walkdown inspection activities were experienced and knowledgeable of the site CLB. Personnel were also trained to perform the visual inspections and met the knowledge requirements specified in EN-DC-170 and Appendix C of NEI 12-07. Team members associated with the flooding walkdowns also satisfactorily completed the INPO's NANTEL Generic Verification Walkdowns of Plant Flood Protection Features lesson and were knowledgeable of the 10 CFR 50.54(f) letter dated March 12, 2012 (Ref. 10.1) and the NRC RAI (Ref. 10.2).Entergy personnel who provided walkdown oversight were trained to perform the visual inspections and were qualified to the requirements specified in EN-DC-170 and NEI 12-07.7.0 WALKDOWN RESULTS A total of 135 walkdown packages were associated with the walkdowns completed for ANO Unit 1. This set includes 68 packages for the 2012 walkdowns, with each package containing a single feature. The features and attributes walked down as part of this package are categorized by flood protection type (incorporated passive, temporary passive, incorporated active, and temporary active) as shown in Table 1 below: Table 1: Summary -Features Included in the Walkdown Scope Flood Protection Type Total Number of Features Total Number of Attributes Passive -Incorporated 67 920 Passive -Temporary 0 0 Active -Incorporated 1 12 Active -Temporary 0 0 The total set of walkdown packages also includes 5 packages for the 2013 walkdowns and 62 walkdown packages for the 2014 walkdowns.
The features that were inspected are listed below: " Unit 1 Auxiliary Building, EL. 317' -Reinforced Concrete Walls and Floors* Unit 1 Auxiliary Building, EL. 335' -Reinforced Concrete Walls, Floors, and Ceilings" Unit 1 Auxiliary Building, EL. 354' -Reinforced Concrete Walls and Floors iCALC-AN01 -CS-1 2-00003 1 ENERCON Entp r REV. 1 y s " Et" Page 16 of 19" Unit 1 Auxiliary Building -Floor Drains and Check Valves" Unit 1 Auxiliary Building -Sumps and Sump Pumps* Unit 1 Auxiliary Building -Roof Drains" Unit 1 Intake Structure Building" Unit 1 Reactor Building Tendon Gallery, EL. 317' -Reinforced Concrete Walls and Floors" Unit 1 Reactor Building, EL. 336'-6" -Reinforced Concrete Walls" Unit 1 Reactor Building, EL. 357' -Reinforced Concrete Walls* ANO Emergency Diesel Fuel Tank Vault -Reinforced Concrete Walls, Floors, and Ceilings* ANO PASS Building -Reinforced Concrete Walls* ANO Emergency Cooling Pond Intake Structure* ANO Emergency Cooling Pond Discharge Structure" ANO Site Yard Drainage* ANO Site Yard Manway* ANO Start-up Transformer
- 2 Bus Duct Attributes associated with the features are detailed in the walkdown packages.
Also, a reasonable simulation was performed for Section 6 of the ANO Unit 1 operating procedure for natural emergencies.
7.1 Deficiencies
As stated in NEI 12-07 (Ref. 10.4), a deficiency exists when a flood protection feature is unable to perform its intended flood protection function when subject to a design basis flooding hazard. During the flooding walkdowns for ANO Unit 1, there were several conditions of features that did not meet the NEI 12-07 acceptance criteria and, therefore, entered into the CAP. The following are exam pies of deficient or potentially deficient conditions that were observed in the flood protection features; the majority of which were related to penetration seals: " Degraded or missing seals at piping penetrations
- Degraded or missing internal and external seals for conduits* Degraded or missing seals at HVAC penetrations" Degraded hatch gaskets" Missing removable flood closure plate for HVAC duct* Floor drain system that cross-connects between flood protected areas and non-flood protected areas* Flood pathways through abandoned-in-place systems" Ground water intrusion through building joints and penetrations
7.2 Observations
Condition reports that were written due to a potential deficiency for a flood protection and mitigation feature were input into the CAP. Based on the operability determinations associated with the condition reports, features were either ECALC-AN01 -Cs-i 2-00003 SENERCO 'REV. 1____ .____-___,__.,_o
_ c,._, , .7t Page 17 of 19 determined to be operable as found, promptly repaired to restore operability, or addressed with compensatory measures to maintain operability.
7.3 Corrective
Actions In 2012 there were no observations identified that required actions to address a deficiency.
The CAP did initiate a work order to repair a watertight door in order to restore available flood margin back to design conditions.
The watertight door was observed to be in a degraded condition with evident gaps between the door and door seal at the top of the door. This observation was not a deficiency as the gap was above the CLB flood level of 361'.In 2014 deficient conditions that were observed in the flood protection features were either promptly repaired or addressed with compensatory measures.
Repairs included installing or replacing flood seals and isolating abandoned-in-place equipment.
The compensatory measures included fabricating and properly staging temporary flood barriers and staging seal material to be installed in the event of extemal flooding.7.4 Flood Protection Features Not Inspected Flood protection features that were determined to be inaccessible could not be visually inspected.
These features included wall areas behind installed equipment and rooms with high dose rates as determined by Radiation Protection (RP).Inaccessible features were evaluated by document reviews and/or by comparison with the material condition of surrounding or similar features.
These evaluations established reasonable assurance that the inaccessible features can perform their design basis function during an external flood.During the 2012 walkdowns, a number of features were considered restricted access and were unavailable for inspection.
These features were documented in the site CAP in 2012 and were inspected at later date (Ref. 10.8), as shown in Table 2 below: Table 2: 2012 Summary -Restricted Access Features Unable to be Inspected Unit I Restricted Access Listing Restricted Access Area & Reason Means to Address Features Unit 1 Aux Building Room 3 El 317 -Locked High Radiation Area Walkdown performed on Required to verify Walls and September 12, 2013 Penetrations Unit 1 Aux Building Room 76 EL 354' Need to remove insulation Walkdown performed on Penetration 76-0050 & 0082 to verify penetration seal September 12, 2013 Unit 1 Reactor Building EL 336'-6" Operating at power Walkdown performed on-Required to verify Walls and September 12, 2013 Penetrations Unit 1 Reactor Building EL 357' Operating at power Walkdown performed on-Required to verify Walls and September 12, 2013 CALC-ANO1 -CS-1 2-00003 ENERCON Cf 0 N _ REV. 1 J..-d Ey i aPage 18 of 19 Penetrations Unit 1 Aux Building Tank Vaults Restricted hatch access Walkdown performed on Rooms 16A, 16B, 16C, 16D El 335 and High Radiation Area September 11, 2013-Required to verify Walls and Penetrations
8.0 AVAILABLE
PHYSICAL MARGIN As indicated in NEI 12-07, Section 3.12 (Ref. 10.4), the NRC is no longer expecting the Recommendation 2.3: Flooding Walkdowns to include an evaluation of the cliff-edge effects at the site. The APM has been determined and documented on the walkdown record forms (Ref. 10.10). The APMs provided on the walkdown record forms will allow flood hazard reevaluations to be completed in response to the NRC's Recommendation 2.1: Flooding.No APMs documented in the walkdown record forms were considered to be "small".9.0 NEW FLOOD PROTECTION SYSTEMS None.
10.0 REFERENCES
10.1. N RC Letter to Licensees, dated March 12, 2012, "Request for Information Pursuant to Title10 of the Code of Federal Regulations 50.54(0 Regarding Recommendations 2.1, 2.3, and 9.3 of the Near Term Task Force Review of Insights from the Fukushima Dai-ichi Accident" 10.2. NRC Letter, dated December 23, 2013, Request for Additional Information Associated with Near-Term Task Force Recommendation 2.3, Flooding Walkdowns; Accession No. ML1 3325A891 10.3. NRC Generic Letter 88-20, dated September 8, 1995, ANO Summary Report, Unit 1, Individual Plant Examination of External Events (IPEEE) for Sever Accident Vulnerabilities 10.4. NEI 12-07, Rev. 0-A, "Guidelines for Performing Verification Walkdowns of Plant Flood Protection Features" 10.5. EN-DC-170, Rev. 000, "Fukushima Near Term Task Force Recommendation
2.3 Flooding
Walkdown Procedure" 10.6. SAR-U1, "Unit 1 Safety Analysis Report", SAR Amendment 26 10.7. OCAN111302, dated November 26, 2012, "Supplemental Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding the Flooding Aspects of Recommendation 2.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident" is CALC-ANO1 -CS-1 2-00003 aENERCON REV. 1 En teWPage 19 of 19 10.8. 1CAN111202, dated November 27, 2012, "Flooding Walkdown Report -Entergy's Response to NRC Request for Information (RFI) Pursuant to 10 CFR 50.54(f)Regarding the Flooding Aspects of Recommendation 2.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident", Arkansas Nuclear One -Unit 2, Docket No. 50-313, License No. DPR-51 10.9. OCAN01 1404, dated January 31, 2014, "Update to Response to NRC 10 CFR 50.54(f) Request for Information Regarding Near-Term Task Force (NTTF)Recommendation 2.3, Flooding -Review of Available Physical Margin (APM)Assessments", Arkansas Nuclear One -Units 1 and 2, Docket Nos. 50-313 and 50-368, License Nos. DPR-51 and NPF-6 10.10. OCAN041410, dated April 30, 2014, "Revised Response to NRC 10 CFR 50.54(f)Request for Information Regarding Near-Term Task Force (NTTF)Recommendation 2.3, Flooding", Arkansas Nuclear One -Units 1 and 2, Docket Nos. 50-313 and 50-368, License Nos. DPR-51 and NPF-6 11.0 ATTACHMENTS None